The invention relates to differential temperature engines previously invented by the author (U.S. Pat. No. 3,846,984, 1974) and in particular to solar differential temperature engines especially adapted to operate in space in the absence of gravity.
Differential temperature engines operate through a vapor pressure differential between a relatively cold chamber and a relatively warm chamber containing a low boiling point liquid. The operation of the engine requires an evaporation of the liquid in the warm chamber and a condensation of the vapor back to a liquid in the cold chamber. The liquid which condenses in the cold chamber must be returned to the warm chamber for the continuous operation of the engine. This occurs either through the force of gravity when the condensor chamber is at a higher level than the evaporator chamber, or through the action of a pump when the condensor chamber is at a lower level than that of the evaporator chamber. Gravity is essential not only for the return of the liquid by force of gravity but also for the return of the liquid by the action of a pump. This is caused by the fact that the condensation of vapor into a liquid in the cold chamber occurs through the formation of small liquid droplets upon the inside surfaces of the cold chamber. In the presence of gravity the droplets accumulate in the lowest portion of the condensor chamber to form a single body of liquid. A small stationary pump operating at the lowest point of the condensor chamber can transfer the liquid from the cold to the warm chamber. In the absence of gravity, however, most of the liquid droplets remain dispersed and could not be reached by a pump operating in a single area. The transfer of most of the condensed liquid from the cold condensor chamber back to the warm evaporator chamber by pump or gravity means would therefore be impossible in the absence of gravity. The present invention solves this transfer problem by eliminating the need for the transfer of the liquid. This is accomplished by the provision of reversible means which enable each chamber to function alternatively as a warm evaporator chamber and as a cold condensor chamber. Thus, when most of the available liquid accumulates through condensation in the cold chamber, the functions of the chambers are reversed, i.e., the cold chamber (containing most of the liquid) functions as a warm evaporator chamber, and the warm chamber (which has lost most of its liquid) functions as a condensor chamber. The evaporator warm chamber would thus always contain sufficient quantities of working low boiling point liquid, and the engine would function continuously without the direct transfer of liquid from chamber to chamber.
The objective of the present invention is to provide a differential temperature solar engine which can function continuously without the direct transfer of liquid from chamber to chamber.
An additional objective of the present invention is to provide a reversible differential temperature solar engine which can function in the absence of gravity in space.
An additional objective of the present invention is to provide an engine which can function during the reversal of relative temperatures of the cold and warm chambers.